38 is the natural number following 37 and preceding 39.

Cardinal	thirty-eight
Ordinal	38th (thirty-eighth)
Factorization
Roman numeral	XXXVIII
Binary	100110
Hexadecimal	26

38! - 1 yields 523022617466601111760007224100074291199999999, which is a factorial prime.

There is no answer to the equation φ(x) = 38, making 38 a nontotient.

38 is the sum of the squares of the first three primes.

37 and 38 are the first pair of consecutive positive integers not divisible by any of their digits.

In astronomy

• The Messier object M38, a magnitude 7.0 open cluster in the constellation Auriga
• The Saros number of
  • the solar eclipse series which began on -1729 June 26 and ended on -431 August 14. The duration of Saros series 38 was 1298.1 years, and it contained 73 solar eclipses.
  • the lunar eclipse series which began on -1408 April 16 and ended on -111 June 3. The duration of Saros series 38 was 1298.1 years, and it contained 73 lunar eclipses.
• The New General Catalogue object NGC 38 , a spiral galaxy in the constellation Pisces

In other fields

Thirty-eight is also:

• The atomic number of strontium
• The number of slots on an American Roulette wheel.
• The number of games that each team in the current English Premiership, the top division in English Association Football, plays in a season
• Bill C-38 could legalize gay marriage in Canada.
• The year A.D. 38, 38 BC, or 1938.